AOL has found that the one problem with an ad-supported model is slowdown in ad revenue, reports The New York Times.

It's been just over a year since AOL ended its reliance on paid subscriptions and opted to pin its hopes on ad income. But the online ad market is diversifying, and portals no longer dominate the online world. Instead, social networks and search are the beginning points for users' online behavior.

AOL says the slowdown in revenue growth this past quarter - 16 percent versus 40 percent in quarters past - is not an indicator of things to come. Execs say it was caused mainly by redesigns and reconfiguring being done to portions of the AOL empire.

The ad sales folks at AOL say the company is finally at a point where it can realistically compete with Google and others. Still, others say the shift from subscriptions to advertising could spell trouble for AOL in the long run.